Support structures are used to sustain a load either continuously or over repeated intervals. For example, a floor structure may be used to continuously sustain a load provided by the gravitational force of static objects placed on the floor structure. Bridges are used to sustain a load over repeated intervals, such as when objects repeatedly travel across the bridge. Loading ramps are used to sustain a load as objects pass up or down the loading ramp. Likewise, walls may sustain a load parallel to the ground such as heavy winds or moving objects contacting the walls.
In certain situations, support structures such as these discussed above may indefinitely remain in a static condition. However, other applications for a support structure may require that it be extendable and retractable for various reasons. As one example, it may be a requirement that a support structure be portable, and to enhance the portability of the structure it may be desirable to reduce the lengthiest dimension of the structure-by retracting it when it must be transported. Then, when the structure is positioned where it must support a load, the structure is extended so that the load can be placed on the structure.
Providing a support structure that can be retracted and extended as necessary requires that the support structure not be a rigid unitary structure. Instead, the support structure must provide retractability and extendibility by incorporating flexibility into the design. However, the support structure must also be able to sustain the particular load that will be applied to the structure. Thus, such a support structure must address at least these two contradictory constraints.